This is a 100ml bottle of Hudy Ultimate Silicone Oil, in 400cst. HUDY Premium Silicone Oils are manufactured in Europe by a specialized silicone oil premium manufacturer and were created exclusively for HUDY. Each batch of ultimate oil is laboratory tested and calibrated to ensure the highest possible consistency and quality from batch to batch. Based on the industry-proven cSt rating, the new line of oils will be easy to identify, adjust, and feel.